Gelatin compositions containing a triazine type hardener and an aliphatic mono- or dicarboxylic acid

ABSTRACT

Photographic gelatin layers are hardened by trisacryloyl or sulfonyl hydroxyltriazine compounds. The hardening reaction is accelerated by the addition of aliphatic carboxylic acids.

United States Patent {54] GELATIN COMPOSITIONS CONTAINING A TRIAZINE TYPE HARDENER AND AN ALIPI'IATIC MONO- OR DICARBOXYLIC ACID 2 Claims, No Drawings [52] U.S.Cl

260/ll7, l06/l25 [5|] lnt.Cl G03c H30 [50] FieldoiSearch 96/lll;

[56] References Cited UNITED STATES PATENTS 3,497,358 2/1970 Sieg etal. 96/! ll Primary Examiner-Norman G. Torchin Assistant Examiner-Won H. Louie, .lr. Attorney-Connolly and Hutz ABSTRACT: Photographic gelatin layers are hardened by trisacryloyl or sull'onyl hydroxyltriazine compounds. The hardening reaction is accelerated by the addition of aliphatic carboxylic acids.

GELATIN COMPOSITIONS CONTAINING A TRIAZINE TYPE HARDENER AND AN ALIPHATIC MONO- R DICARBOXYLIC ACID The invention relates to a process for hardening gelatin layers, particularly photographic layers, with N,N', N"- trisacryloylor N,N', N"-trisvinyl-sulfonyl-l,3,5-hexahydrotriazine in the presence of aliphatic carboxylic acids as hardening accelerators.

A large number of cross-linking or hardening agents for gelatin have already been described. Thus, for example, metal salts such as chromium, aluminum or zirconium salts, aldehydes or their derivatives, particularly formaldehyde, dialdehyries, mucochloric acid, diketones, quinones and chlorides of dibasic organic acids and dianhydrides are already known. Compounds which contain at least two heterocyclic, threemembered rings which can easily be split, such as ethylene oxide or ethylene imine may be used as hardeners for gelatin. Furthermore, polyfunctional methanesulfonic acid esters and bis-a-chloroacyl-amido compounds have been described for this purpose.

Compounds having two or more acrylic acid amide or vinylsulfonyl groups in the molecule have also been described as hardeners for photographic gelatin layers, for example N,N', N"-trisacryloylhexahydrotriazine or N,N', N"-trisvinylsulfonylhexahydrotriazine.

Recently, high molecular weight-hardening agents such as polyacrolein and its derivatives or copolymers as well as alginic acid derivatives have been described, which are used particularly as diffusion-resistant hardeners.

Many of the above mentioned compounds, however, are of limited utility, particularly for photographic purposes. Some are photographically active while others alter the physical properties, for example they cause brittleness of the gelatin layers. Others tend to cause discolorations or changes in the pH during the hardening reaction. It is, above all, particularly important that the hardening of photographic layers should reach its maximum as soon as possible after drying so that the penetration of the developer solution will not constantly change, as e.g. in the case of mucochloric acid or formaldehyde.

For these reasons, the need still exists, particularly in photography, to find sufiiciently rapid and photographically inert hardeners. The disadvantages of known hardeners can, of course, be overcome by the addition of hardening accelerators because the concentration of the hardeners can be greatly reduced when such compounds are used.

It is among the objects of the invention to provide hardeners for gelatin layers, particularly photographic layers, which enable the layer to harden completely within a sufficiently short time and which are photographically harmless. Another object of the invention is to provide hardening accelerators which in combination with known hardeners will shorten the hardening time or enable the concentration of hardener to be reduced.

We now have found a process for hardening gelatin layers by the addition of N,N', N"-trisacryloyl-l ,3,5-hexahydrotriazine to the finished layer which is to be hardened, or to the casting solution for the layer which is to be hardened, and subsequent application on a layer support and drying, wherein in addition to the hardening agent an aliphatic carboxylic acid having up to carbon atoms or its salt are added to the layer.

Alkali metal salts such as sodium salts of aliphatic carboxylic acids containing up to three carbon atoms, for example acetic acid, formic acid or propionic acid are particularly advantageous.

The effect of the hexahydrotriazine hardener is greatly enhanced by the addition of the aliphatic carboxylic acids or their salts. For a given concentration of hardener, the hardening time is considerably reduced or for a given hardening time the use of a much smaller concentration of hardener is sufficient.

The hardener is added to the layers, or to the casting solutions for the layers, in quantities of 0.1 to 3 or 0.3 to 1.5 percent by weight, based on the dry weight of gelatin.

EXAMPLE 1 A silver bromide gelatin emulsion which contains per kilogram of emulsion 8 g. of silver bromide, g. of gelatin, 24 g. of the color coupler of the following formula: 1

ammo o-N-oo-cmcoN- II II -COOII COOH and 1.5 percent by weight of N,N', N"-trisacryloyl-l,3,5-hexahydrotriazine, based on the dry weight of gelatin, is divided into three parts.

Part 1: is used without further additive as a control sample;

Part 2: 3 percent by weight of sodium acetate, based on the dry weight of gelatin are added to the emulsion;

Part 3: 3 percent by weight of sodium propionate based on the dry weight of gelatin are added.

The above casting solutions are adjusted to a pH of 6.2 and cast on layer supports of cellulose triacetate. The dry layers have a layer thickness of 10 m.

The melting point of the layers is determined as follows: The supported layer is half dipped in water which is continuously heated to C. The temperature at which the layer runs off the support (formation of streaks) is taken as the melting point or melting or melting-off point. The melting-off points of layers hardened according to the invention were determined in other tests after 5 minutes treatment with a 5 percent soda solution immediately after drying or after the storage indicated above. The water used for measuring the melting points was adjusted to pH 3.2 by the addition of sulfuric acid.

After drying, one part of the samples was stored for 3 days in an airtight package at 20 C. (storage method A).

Another part was kept for 36 hours at 56 C. and 40 percent relative humidity (storage method B). I

The melting points of the layers were then determined as above. The results are shown in the table below:

TABLE 1 Melting points of the layers A silver iodobromide gelatin emulsion (3 mols of silver iodine) which contains 80 g. of silver halide and 80 g. of gelatin per liter of emulsion is divided into three parts.

Part 1: 0.1 percent of N,N', N"-trisacryloyl-hexahydrotriazine based the dry weight of gelatin is added.

Part 2: 0.25 percent by weight of the same hardener is added.

Part 3: 0.4 percent by weight of the same hardener is added.

The emulsion samples described above are again subdivided. One part is left without further additives and serves as control sample. In the other part, 3 parts by weight of sodium acetate, based on the dry weight of gelatin, are added. The emulsion samples are adjusted to pH 6.2 and the casting solutions are cast on a cellulose acetate support. The dry layers have a thickness of 10 pm.

The melting points of the layers are determined as described in example i. The results are shown in the following table 2. The storage conditions indicated in the table are the: same as those indicated in example 1.

Similar results are obtained with emulsion samples of the same emulsion containing 0.5 and 0.7 and 1 percent by weight, respectively, of the hardener and 2 percent by weight of sodium acetate solution.

After several days storage of these samples in airtight packages at 20 C., the melting points of the layers shown in the following table 3 are obtained:

TABLE 3 Amount of 1,3,5-lris- Melting points of the layers acryloyltriazine after contained in the emulsion 1 days 2 days 3 days storage 0.50% 39 C. 83C. 100C. 0.75% 40 C. 100C. 100C. 1.00% 43C. 100C. 100C.

EXAMPLE 3 A silver bromide gelatin emulsion which contains 20 g. of silver bromide and 45 g. of gelatin per layer is divided into two parts.

Part 1: 3.5 ml. ofa 5 percent aqueous solution 0fN,N', N"- trisacryloyl- 1,3,5-hexahydrotriazine (pH 6.5, corresponding to an addition 0f0.75 percent by weight based on the gelatin) are added.

Part 2: The same quantity of hardener as in part 1 is added and in addition 20 ml. of a 1N succinic acid solution and ml. ofa 2N NaOlHl solution.

The two casting solutions are applied onto a support of cel' lulose triacetate and dried.

The melting point of the layers is determined as described above and the scratch resistance of the emulsions is deter mined after storage at 35 C. and 80 percent relative humidity. Details are shown in table 4 below.

TAB LE 4 Abrasion resistance (g) Melting point C C.)

0 hr. 18 hr. 36 hr. 72 hr. 0 hr. 18 hr. 36 hr.

Part

Similar results are obtained when sodium succinate or sodium maleate is added as hardener. The concentrations are similar.

In the present emulsion, the accelerating effect is preserved even when color couplers are added to the layer in the usual concentrations.

EXAMPLE 4 An emulsion containing 20 g. of silver bromide and 23.5 g. of gelatin per 512 g. of emulsion is divided into three parts A, B and C. 6.7 ml. ofa 5 percent solution ofN,N', N"-trisvinylsulfonylhexahydro-l ,3,5-triazine (pl-i=6.5) for every 512 g. (=l.4 percent by weight based on gelatin) are added to the first part. The same quantity of hardener is added to emulsions B and C in addition to 20 ml. of 1N maleic acid and the necessary quantity of caustic soda solution to adjust the pH to 6.5 or

The emulsions are applied to a layer support of cellulose triacetate (quantity of emulsion: 112.5 g./m.'). The abrasion resistance of the emulsion layers is determined by the process described in example 3.

TABLE 5 Part Abrasion resistance 0 h 18 h as h 12 n A so 400 600 150 a [pH==6.5) 200 800 900 c tpH=7 300 850 950 EXAMPLE 5 The emulsion according to example 4 is divided into two parts:

Part 1: 13.4 ml. of a 5 percent aqueous solution of N,N', N"-tri.svinylsulfonylhexahydro-1,3,5-triazine (pH=6.5) are added.

Part 2: Addition of 13.4 ml. ofa 5 percent solution of N,N', N"-trisvinylsulfonylhexahydro-l ,3,5-triazine (pH=6.5 20 ml. of succinic acid and 10 ml. of NaOH per 512 g. of emulsion.

The emulsions are applied to a cellulose acetate support according to example 4. The abrasion resistance is tested after storage at a relative humidity of 80 percent at 35 C.

TABLE 6 Part Abrasion resistance 0 h 18 h 36 h 72 h We claim: 

2. The process of claim 1, wherein the aliphatic monocarboxylic carboxylic acid or its salts having up to three carbon atoms. 